Lead Salt Research Articles

Iodine- and Oxygen-Free Sensitization Process for VPD-PbS:IO Detectors

Uncooled lead salt detectors have significant advantages in developing the next generation of infrared detectors with SWaP3 features. Herein, a one-step pure nitrogen (N2) sensitized process is proposed to simplify the fabrication process for a wafer-scale lead sulfide (PbS) film fabricated by a modified low-temperature vapor physical deposition (VPD). A room-temperature peak detectivity of 4 × 1010 Jones is achieved after one-step pure N2 sensitization process carried out for VPD-PbS:IO films, which is comparable to the detectors fabricated from the standard chemical bath deposition (CBD) process. The VPD fabrication technology with an iodine-free sensitization process provides an available route for promoting the commercial application of uncooled infrared detectors.

High-performance PbS detectors sensitized from one-step sensitization

Two-step sensitization is the key technique for achieving high-performance uncooled lead-salt infrared photoconductive detectors fabricated from vapor physic deposition (VPD) method. However, the commercialization of these devices is inhibited by the intricate sensitization processes, especially the iodination step, which requires precise control over high concentrations of iodine vapor. Herein, a one-step sensitization technique was proposed to improve the reliability of lead sulfide (PbS) detectors manufactured from VPD method. Moreover, the dependence of the detectivity on sensitization parameters involving the oxygen concentration, time, and temperature, was established and interpreted based on extensive studies on the sensitization of lead salt devices. The feasibility of the simplified sensitization was demonstrated by a room-temperature peak detectivity of 2.47 × 1010 cm Hz1/2 W−1 at 2.7 μm attained at 430 °C for 10 min in 50 % oxygen ambient. The evolution of phase, microstructure and electrical properties confirms the enhanced performance results from the improvement in PbS crystal quality as well as the formation of Pb3O2I2 and Pb2(SO4)O from high-temperature recrystallization. Therefore, the one-step sensitization paves a way for accelerating commercialization of lead-salt detectors fabricated by VPD technique.

Biowaste-alkaline lignin and GO integrated polysulfone ultrafiltration membrane fabrication for Pb2+ and Eosin Y dye removal

The textile industry uses a variety of lead compounds, including lead acetate for textile dyeing, lead chloride for lead salt manufacture, and lead molybdate for pigments. Furthermore, Eosin Y, a water-soluble red dye, is commonly used in textile dyeing and ink production. The presence of Eosin Y dye and lead metal ions in textile industry effluents is prevalent. Integrating adsorbent nanofillers into the membrane matrix serves a dual purpose of membrane filtration and adsorption functionalities. In this study, Lignin/GO incorporated polysulfone composite membranes were fabricated with the phase inversion method and with PEG 6000 as a pore-forming agent. Zeta potential, pure water flux, mechanical strength, and hydrophilicity of the membranes were all improved by the integration of lignin and GO into the membrane matrix. Filtration operations were carried out using an aqueous solution containing both lead (Pb) and Eosin Y dye. Additionally, the influence of their electrostatic interactions on membrane fouling and the regeneration process was examined. The electrostatic interaction, specifically the linking effect between Pb2+ ions and negatively charged Eosin Y molecules, formed larger Eosin-Pb complexes. This led to an enhanced Pb2+ removal through membrane filtration. During the second filtration cycle, the membrane, comprising 0.75 wt% lignin and 0.75 wt% GO, achieved 100 % removal of Pb2+ ions and an 81 % rejection of Eosin Y. A Pb2+ adsorption study was conducted using the optimized lignin/GO membrane. The adsorption process was investigated through Langmuir and Freundlich isotherms exhibiting a superior fit and assured R2 values of 0.977 and 0.994, respectively. According to the isotherm data the adsorption process involves multilayer physisorption. The developed Lignin/GO-incorporated polysulfone composite membranes hold the promise for tackling issues in a variety of domains, including water treatment and biomedical applications, demonstrating versatility and ability to make positive impacts across industries.

Temperature dependence of infrared photoresponse from lead sulfide film grown by chemical bath deposition

Due to the lower Auger recombination coefficient of lead salts, the study of room temperature infrared detectors based on lead salt is reemerges as a hot research topic. In this paper, we prepared polycrystalline lead sulfide (PbS) films using chemical bath deposition and fabricated a photovoltage infrared detector with Si. Different from normal PbS photodetectors, which usually show positive photoconductivity, our device demonstrated both positive and negative photoconductivity under 1550 nm laser illumination. The switching of positive and negative photoconductivity was found to be depended on temperature and applied bias. We proposed that the change of photoconductivity is due to the electron traps from S vacancies. Furthermore, we also tested the photoresponse under infrared blackbody radiation, which confirms that the device exhibits high sensitivity. The temperature dependence of PbS infrared photodetector demonstrated in this paper could be useful for applications involving focal array planes based on lead-related materials.

Revealing the long way towards lead-free plastic in China through dynamic material flow analysis of lead salt heat stabilizers in PVC products

The use of lead salt heat stabilizers (LHSs) in plastics are restricted or even prohibited owing to their high toxicity. However, little information is available on its industrial metabolism. A dynamic material flow analysis of LHSs indicates that China consumed 2952 kt LHSs between 1958 and 2020. Moreover, at present, 1020 kt of these is being used in polyvinyl chloride (PVC) products, 1007 kt is in landfills, and 681 kt is in the environment. For China to realize lead-free primary plastics by 2040, 2050, and 2060, the LHSs consumption should be reduced by at least 13 %, 10 %, and 9 % annually, respectively. Certain LHSs would gain new life with PVC recycling. Therefore, approximately 30 years would be required for LHSs to disappear completely after their use is stopped. With improvements in the plastic recycling rate, it is necessary to use chemical recycling and other methods to separate the hazardous additives such as LHSs and reduce the circulation of toxic substances.

Near-infrared self-assembled laser based on Ag<sub>2</sub>Se quantum dots

The development of colloidal near-infrared quantum dots (QD) lasers has been hindered by the high state degeneracy of lead salt QDs and the difficulty in coupling colloidal quantum dots to the resonant cavity. In this study, we show that above challenges can be addressed by the self-assembly laser based on Ag<sub>2</sub>Se QDs. Ag<sub>2</sub>Se QDs with the lowest quantized states 2-fold degeneracy are used to replace lead salt quantum dots to achieve low threshold near-infrared optical gain. We employ the finite element method to deeply analyze the mode field distribution and oscillation mechanism of the coffee-ring microcavity. Our results reveal that the light field oscillates in a zig-zag path along the cross-sectional area, indicating strong coupling between the QDs and the cavity mode. Furthermore, we investigate the relationship between cavity length and free spectrum range and laser emission wavelength. Leveraging this relationship and the gain spectrum characteristics of Ag<sub>2</sub>Se QDs, we design a single-mode near-infrared laser and conduct a comprehensive analysis. Using simulation results to fabricate a single-mode near-infrared Ag<sub>2</sub>Se QD coffee-ring microlaser, which exhibits a linewidth of 0.3 nm and a threshold of 158 μJ cm<sup>-2</sup>. Currently, it holds the record for the lowest laser threshold among near-infrared colloidal QD lasers. Increasing the laser cavity length, resulting in an increase in the emission wavelength from 1300 nm to 1323 nm. In addition, the toxicity of Ag<sub>2</sub>Se QDs is remarkably negligible. Our work promotes the development of environment-friendly near-infrared lasers to practical lasers.

Prophylactic Efficacy of <i>Allium sativum</i> Essential Oil on Hepatic Tissues of Mice Model Exposed to Inorganic Lead Salt

Hypothesis: Lead is a pervasive environmental pollutant that is major threat for human health. Allium sativum essential oil could impart possible protection from Lead Nitrate (LN) as it contains organosulfur compounds which possess various pharmacological potential including antioxidant, anti-inflammatory, anticancer, anti-apoptotic and other activities as well. Parameters Studied: The ameliorative role of Allium sativum essential oil on hepatic tissue damage caused by Lead nitrate was evaluated through oxidative stress, biochemical parameters, oxidative Stress Index (OSI) and hepatic biomarkers. Methodology and Results: In this study, six groups of animals were taken. These groups were: control animals, toxicant treated animals (LN), LN + plant oil low and high dose treated animals, LN + silymarin treated animals and LN + vehicle oil control group. Lead nitrate exposure significantly decreased the antioxidant molecules mainly SOD, CAT, Gpx, GSH, GST, TPC and increased the lipid peroxidation content, Oxidative Stress Index (OSI), liver indices, Total Cholesterol Content (TCC) and biochemical parameters [ALT, AST, ALP] In addition to this, Lead nitrate increased the level of hepatic biomarkers such as cytp4502E1, 5’-nucleotidase, and γ-glutamyltranspeptidase and decreased the cytb5 content in hepatic tissues. Conclusion: Antioxidant activity of Allium sativum Essential Oil (ASEO) prevented oxidative stress and restored the level of liver indices, biochemical parameters, and hepatic biomarkers in Lead nitrate-intoxicated mice. Therefore, ASEO can be considered as a promising protective strategy against Lead nitrate-induced hepatotoxicity.

Revealing different lead species of PbCl2, Pb(NO3)2, PbSO4 and PbCO3 poisoning effects on Mn-Ce/CuX catalyst for low-temperature NH3-SCR of NO

For the sintering flue gas in steel industry, selective catalytic reduction (SCR) of NOx using NH3 at low temperature in the presence of heavy metals is still a challenge. In this study, the toxicity effects of lead salt species (PbCl2, Pb(NO3)2, PbSO4, PbCO3) on Cu-exchanged zeolite X doped with Mn-Ce catalysts (MCCX) were investigated. All catalysts exhibited poor low-temperature SCR performance within 75–225 °C after Pb poisoning, and the poisoning effects of PbCl2, Pb(NO3)2, PbSO4 and PbCO3 on MCCX catalyst varied. The PbSO4 had the most serious poisoning on MCCX catalyst, while PbCO3 had poisoning effect on catalysts even at 300 °C. Lead species poisoning had bad impact on the structure of zeolite X on MCCX catalyst, and caused some agglutination of Cu species. Likewise, the Pb species might primarily occupy the active site of Mn and Cu species and influence the redox property of catalysts, thereby obstructing the redox and oxidation cycles on catalysts surface. In addition, the PbCl2 and PbNO3 species predominantly affected the Brønsted acid sites and occupied the Cu or Mn active sites, inhabiting the absorption and conversion of nitrites and nitrates on the catalyst surface. Moreover, PbSO4 and PbCO3 species mainly impacted the adsorption of NO + O2 and the conversion of nitrites and nitrates on the catalysts.

Wide‐Wavelength Tunable Mid‐Infrared Lasing Based on Black Arsenic Phosphorus

AbstractMid‐infrared (MIR) semiconductor laser sources are essential for applications in gas detection, infrared imaging, and high‐speed free space optical communications. At present, the dynamic wavelength tunability of MIR lasers based on lead salt, antimonide, and quantum cascade lasers is limited and their compact size as well as heterogeneous integration are still challenging. Two‐dimensional (2D) materials, used as optical gain materials, have the flexible tunability and compatible van der Waals integrations—providing many new possibilities for constructing MIR laser sources of large tunability and high integration. Here, wide‐wavelength tunable MIR vertical cavity surface emitting lasers (VCSELs) integrated on silicon substrates are realized based on 2D black arsenic phosphorus (b‐AsxP1−x). The emission wavelength of the optically pumped laser device is demonstrated to be tuned from 3.42 to 4.65 µm at room temperature, which could be controlled by adjusting the alloy composition and thickness of the gain media b‐AsxP1−x. The tunable MIR VCSEL device would pave the way for further exploration of 2D materials‐based IR lasers working as on‐chip light sources.

Near-infrared self-assembled laser based on Ag<sub>2</sub>Se quantum dots

The development of colloidal near-infrared quantum dot (QD) lasers has been hindered by the high state degeneracy of lead salt QDs and the difficulty in coupling colloidal QDs to the resonant cavity. In this study, we show that the above challenges can be addressed by the self-assembly laser based on Ag<sub>2</sub>Se QDs. The Ag<sub>2</sub>Se QDs with the lowest quantized states 2-fold degeneracy are used to replace lead salt quantum dots to achieve low threshold near-infrared optical gain. We employ the finite element method to in depth analyze the mode field distribution and oscillation mechanism of the coffee-ring microcavity. Our results reveal that the light field oscillates in a zig-zag path along the cross-sectional area, indicating strong coupling between the QDs and the cavity mode. Furthermore, we investigate the relationship of cavity length with free spectrum range and laser emission wavelength. Using this relationship and the gain spectrum characteristics of Ag<sub>2</sub>Se QDs, we design a single-mode near-infrared laser and conduct a comprehensive analysis. The simulation results are used to fabricate a single-mode near-infrared Ag<sub>2</sub>Se QD coffee-ring microlaser, which exhibits a linewidth of 0.3 nm and a threshold of 158 μJ/cm<sup>2</sup>. Currently, it holds the record for the lowest laser threshold among near-infrared colloidal QD lasers. The increasing of the laser cavity length leads the emission wavelength to increase from 1300 nm to 1323 nm. In addition, the toxicity of Ag<sub>2</sub>Se QD is remarkably negligible. Our work promotes the development of environment-friendly near-infrared lasers toward practical lasers.

Comparison Study of Electrooxidation and Photo-Electroxidation for the Treatment of Solutions Containing Acid Blue 9 Dye

The objective of this study is to investigate the contribution of light energy in the electrochemical oxidation treatment of a solution containing a model molecule, Acid Blue 9 dye (AB 9) using a low-cost electrode elaborated by electrodeposition from a lead salt. The elaboration procedure and the characteristics of the obtained Ti/b-PbO2 electrode are given in the Supplementary Information. First, electrolysis and I-E curves were performed in order to determine the best conditions for dye removal and mineralization. Then the effect of illumination is studied.

Trends and prospects for thermal stabilizers in polyvinyl chloride

AbstractThermal stabilizers are essential for polyvinyl chloride (PVC) processing. It is the emergence of thermal stabilizers that made PVC's applications migrate from laboratory to large‐scale industrial use. Herein we overview the development status of some traditional thermal stabilizers including lead salt, metal soaps, and organotin along with relatively newer thermal stabilizers such as organic thermal stabilizers and metal alkoxides. Taking into consideration the high market demand, opportunities for cost‐effective additives for thermal stabilizers are also briefly discussed. Finally, with the recent shift in focus on thermal stabilizer synthesis and their performance characterization but neglecting mechanical property testing and verification, we put forward application prospect of quantum chemical calculation for the development of PVC thermal stabilizers.

Effect of various types of anions and anionic surfactants on the performance of micellar-enhanced ultrafiltration process in the removal of Pb(II) ions: An optimization with the response surface methodology

In the present study, the micellar-enhanced ultrafiltration (MEUF) process was employed for the removal of Pb2+ ions from aqueous solutions using sodium dodecyl sulfate (SDS) and sodium lauroyl sarcosinate (Sarkosyl) as the anionic surfactants. The performance of Sarkosyl was compared to SDS, a frequently used surfactant in the MEUF processes, to evaluate their efficiency in the removal of lead ions. Sodium chloride (NaCl) was used as the electrolyte and the role of lead salt anions, lead nitrate (Pb(NO3)2) and lead chloride (PbCl2), was also investigated for the first time in the MEUF process. The MEUF process was modeled using response surface methodology (RSM), and experiments were designed and carried out based on the central composite design (CCD). Two categorical variables of anionic surfactants and lead salts, and two numerical variables of Pb2+ and electrolyte concentrations were considered as the studied factors in this design. The process was assessed in terms of its ability to simultaneously maximize Pb2+ rejection and permeate flux. The results showed that increasing the concentration of NaCl significantly reduces the permeate flux, while lead ions concentration has a negligible impact on the permeate flux. The response surface plots also indicated that the effect of the anionic surfactant type on the permeate flux is insignificant. In the studied range of lead concentrations, the highest removals of Pb2+ ions were observed at the concentration of 21 mg/L of Pb(NO3)2 and 0.05 M of NaCl, equal to 79.27% and 94.74% for Sarkosyl and SDS anionic surfactants, respectively.

Identifying the physical mechanisms of polycrystalline lead salt photoconductors

Polycrystalline infrared lead salt detectors exhibit exceptionally high sensitivity near room temperature and, as such, are ubiquitous in commercial instruments such as spectrometers and flame detectors. The underlying physical mechanism behind this remarkable performance has been the subject of speculation for many years. In this treatise, data from work performed at BAE Systems and St. John's Optical Systems and from the published literature are analyzed to identify common mechanisms that contribute to the photoconductivity of polycrystalline lead salt detectors from a multitude of material deposition and process technologies, and it was concluded that much of the behavior can be attributed to surface-related phenomenon. Physical models are proposed to explain the observations. Finally, there is a brief description of measurements related to noise in these complex structures, indicating the importance of ohmic contacts, but the observed low frequency spectral noise density remains a mystery.

-Ferrocenedicarboxylic Acid Salts as Burning Rate Modifiers of Double-Base Propellant

To expand the possibilities of using solid propellants in gas generators or civil- purpose rockets, the properties of new compounds proposed as burning rate modifiers were considered. -ferrocenedicarboxylic acid and its insolubility in water copper, iron, and lead salts were synthesized. The effect of the salts on the burning rate of a double-base propellant was studied. It was shown that individually 3% of copper salt (CFDA) has the most considerable effect on the burning rate, increasing by times at the pressure interval of 1–10 MPa. It is possible to lower the n value in the burning law from 0.71 to 0.21 in a pressure range of 6–15 MPa with use of lead salt. Carbon nanotubes significantly increase the efficiency of FDA salts. An interesting phenomenon was discovered: Iron salt (IFDA) affects the burning rate only at pressure up to 2 MPa, and at higher pressures, but only in combination with a carbon nanotube. IFDA also reduces the efficiency of CFDA. An explanation of that fact was suggested.

Electrodeposition of lead and lead-tin alloy on copper using an eco-friendly methanesulfonate plating bath

Lead coatings were deposited from an electroplating bath contained mainly a lead salt and free methane sulfonic acid (MSA). Electroplating copper samples with a lead-tin alloy was carried out from a plating bath contained a lead salt, a tin salt and free MSA. An organic additive was added to enhance the surface morphology and therefore the appearance of the coated samples. The parameters affected the coating quality like the plating time, current density, temperature and bath composition are optimized. Surface characterization (FE-SEM & EDX) of the formed coating shows a compact dense layer of Pb or Pb–Sn alloy. XRD of Pb–Sn coating shows clear peaks of each lead and tin. The electrochemical properties of the coated samples was investigated using the electrochemical impedance spectroscopy (EIS). The obtained coatings were compared with those obtained using the fluoroborate bath. It is worthy to mention that the presence of the organic additives markedly improved the quality of the lead coating obtained from the methanesulfonate bath so as to have the same quality of the coating obtained from the fluoroborate bath.

Synthesis and Analysis of Anthracene –Lead Titanate composites by Solid State Method

The composition of Anthracene and Lead Titanate is prepared using Solid State method. Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C14H10, consisting of three fused benzene rings. It is a component of coal tar. Lead (II) titanate is an inorganic compound with the chemical formula PbTiO3. It is the lead salt of titanic acid. Lead (II) Titanate is a yellow powder that is insoluble in water. At high temperatures, lead Titanate adopts a cubic perovskite structure. The samples of Anthracene –Lead Titanate composites of suitable mixture ratio are prepared using Solid state method. Crystal structure of the calcined powders and als sintered ceramics were analysed using XRD(X-ray diffraction). The microstructure of the sintered ceramics has been investigated using SEM (scanning electron microscopy).

Probing the effect of a glass network on the synthesis and luminescence properties of composite perovskite glasses [Invited

All-inorganic cesium lead bromide perovskite nanocrystals (PNCs) are highly promising candidates for various optoelectronic and photonic devices. However, poor stability upon exposure to moisture and lead toxicity issues significantly limit their applications. A modern and promising strategy on resolving these issues is the encapsulation of highly luminescent (PNCs) within transparent inorganic oxide glasses. While the encapsulation procedure effect on the development and properties of the so-formed PV-Glasses has been explored in detail, there is lack of understanding the influence of the selected glass composition and network type on the outcome of the synthesis. Herein we report on the synthesis and photoluminescence properties of composite perovskite-glasses upon growing all-inorganic lead halide perovskites within three different types of inorganic oxide glasses. When a silver metaphosphate glass matrix is used it is revealed that the low glass transition temperature of the phosphate glass limits significantly the temperature range of the required post-melting annealing treatment, while the lead salt precursors react with the phosphate entities of the network destroying the stoichiometry of the PNCs. As a result the formation of PNCs is hindered. As a consequence, a double network former borophosphate glass was employed as a suitable host. While annealing treatments at higher temperature were facilitated in this case, it is found that the high silver content becomes an obstacle for the perovskite formation. In view of these findings, cesium lead bromide (CsPbBr3) and cesium lead iodide (CsPbI3) composite perovskite borate glasses were synthesized and found to be suitable hosts. Indeed, such composite glasses exhibit interesting photoluminescence properties that are compared with those of PNCs outside the glass matrix.

Hot-carrier infrared detection in PbS with ultrafast and highly sensitive responses

Traditional infrared semiconductors with direct narrow bandgaps, such as HgCdTe, InGaAs, and lead salts (PbS, PbSe, and PbTe), have been commercialized for decades in various infrared technologies, such as night vision, military communication, and health monitoring. However, traditional infrared (specifically middle- and long-wave infrared) semiconductors suffer from serious noise generation via thermal excitation and external current bias. Although thermal infrared detectors can operate at room temperature, their response speed is very slow, typically on the order of milliseconds or worse, which limits their applications. Herein, we reinvent a classical lead salt semiconductor (PbS) as a room temperature, high speed, and high-detectivity infrared detector. The detection is operated via the self-driven (no bias voltage necessary) photothermoelectric (PTE) effect with a response time reaching 500 ns (limited by the measurement setup)—three orders of magnitude faster than commercial PTE and photoconductive PbS detectors. Furthermore, the physical principle of hot-carrier-dominated heat energy conversion is proposed to understand the unconventional ultrafast response behavior. Combined with high sensitivity at room temperature (noise equivalent power 0.3 pW Hz−1/2) and broadband detection range (0.4–2.3 μm), this hot carrier makes the traditional commercial semiconductor PbS applicable to a class of infrared detection applications.

Assessment of the effect of heavy metal salts on the photosynthetic activity of aquatic plants

The status of the photosynthetic pigments in the aquatic plants Lemna minor L. and Elodea canadensis Michx. under the action of Ni2+, Co2+, Cu2+ and Pb2+ acetate in concentrations 5.00, 2.50, 1.25, 0.62, 0.31, 0.15, 0.07, and 0.03 mg/L was assessed by changes in the fluorescence intensity of chlorophyll a and b and their ratio. It was established that nickel acetate in original solutions in all the above concentrations caused an increase in the fluorescence intensity of chlorophylls a and b in L. minor in relation to the control while the lead salt suppressed it. Co2+ acetate inhibits the fluorescence of chlorophyll a with concentrations in the initial solutions of 0.03 to 0.15 and 2.50 mg/L and that of chlorophyll b at all concentrations, except 0.62, 1.25 and 2.50 mg/L. For E. canadensis it was found that the salts of all metals at all concentrations caused a reduction of the fluorescence intensity of chlorophyll a relative to the control and increased it in the case of chlorophyll b. The exception is the effect of copper and lead acetates with a concentration of 1.25 mg/L, when the fluorescence intensity of chlorophyll b is maintained at the control level. The presence of Ni2+, Co2+, Cu2+, and Pb2+ acetates in all concentrations in the culture medium influences the quantitative and qualitative characteristics of chlorophyll a and b, which indicates a violation of the photosynthesis process. Our data on the change in the chlorophyll a / b ratio leads to a conclusion about degradation of chlorophyll a relative to chlorophyll b after the effect of heavy metals.